Recently, the freshwater shortage and greenhouse effect have become the two global problems and lots of countries are conducting related researches to solve them. The most prospective technology is the integrated CO2 capture and seawater desalination technology, or rather is the CO2 hydrate-based desalination technology. The principle of this technology is that the seawater can form hydrates with CO2 at a certain low temperature and high pressure (heating, depressurization or their combination will make hydrates decompose). Due to the salt-removing effect during the hydrate formation process, the sodion, magnesium ion, chloridion and other ions cannot enter the hydrate crystals and will still concentrate in the liquid. And then, the freshwater can be collected by decomposing the hydrates alone. At present, in the published patent literatures and research achievements, the production and efficiency of hydrate based desalination technology are limited by the hydrate formation situation. And the more important is that this technology requires so much energy to provide a low-temperature environment for hydrate formation. Yet, the storage temperature of LNG (liquified natural gas) is −162° C. and there are such huge cold energy in LNG storage, transportation and gasification for use that can absolutely be used to the refrigeration for hydrate based desalination. Therefore, the present invention uses the CO2 in the flue-gas (which is about 40° C. and made up of 20% CO2 and 80% N2) to form hydrates with seawater combining the LNG cold energy. And it employs a more simple and effective solution to realize the improvement of freshwater productivity and energy utilization efficiency.
The present invention is to provide a system for flue-gas hydrate-based desalination using LNG cold energy. The purpose of the present invention is to realize the large-scale seawater desalination finally by means of a more convenient and effective solution. It makes good use of LNG cold energy to reduce the cost input. And meanwhile, it captures and storages the CO2 to decrease the CO2 concentration and in the atmosphere and reduces the waste heat emission of the flue-gas.